1. Field of the Invention
This invention relates to an apparatus for and a method of collating, sorting and stacking sheets, and more particularly, to the method of "offset collation" using an "offset collator".
2. Description of the Prior Art
The terms "collate" and "sort" have at times been used interchangably in the prior art. Accordingly, so that the description herein-to-follow is clearly understood, some definitions are in order.
To "collate" is to arrange or assemble according to an orderly system of classification, e.g., by page number or order of sheets. Thus, "collating", as the term is used herein, is integrating sheets by classification, and in the case of "collation" the classification generally is by page number. Consequently, "collation" is the act or process of "collating", and a "collator" is an apparatus for so doing.
To form a "set" is to group by classification. Thus, the end product of "collation" is a plurality of "sets."
To "sort" is to put in a given place or rank according to kind or class, e.g., by stacking "sets" and/or placing them such that each is demarcated from the other so as to be easily identified and handled. Thus, "sorting", as the term is used herein, is segregating by "sets." Consequently, "sortation" is the act or process of "sorting", and a "sorter" is an apparatus for so doing.
As far as is known, prior art collators have been derived, or based on two methods of collation. These methods or processes are commonly termed "online collation" and "offline collation".
In collators using the online collation technique, all of the first sheets of a multipage document are produced and transported, one each, to a plurality of discrete bins. Then, all of the second sheets of the multipage document are produced and transported, one each, to the aforementioned plurality of discrete bins. This process is repeated until sets (one each) are built up in the plurality of discrete bins. Generally, collators of this type are designed to interface with an associated copier, duplicator, printer, or like machine. As a consequence, these collators become an integral part of the associated reproduction machine adding to the already substantial overall size thereof.
The size of online collators and offline collators (to be discussed hereinafter) is directly dependent on the number of discrete bins and the physical dimensions thereof. Generally, the number of discrete bins determines the maximum number of sets that can be run in a particular job. The physical dimensions of the discrete bins, characterized by their height, width and depth determine the maximum sheet size that can be processed and the maximum number of sheets per discrete bin.
Since there is an overall physical size limitation, the solution in the prior art machines has been to strike a balance between the maximum number of sets that can be run in a job and the maximum number of sheets that can comprise a set. Thus, in order to meet the physical size requirement, typical prior art machines have a capacity of 20 sets comprising 100 sheets each giving a total sheet capacity of 2,000.
Consequently, the prior art solution to the physical size problem, generally, has been to limit the overall physical size of collators by limiting the total sheet capacity. Nevertheless, machines in the prior art are still large and bulky when compared with their associated reproduction machines.
Thus, there is a need in the prior art for a collator of the online type, i.e., integral with an associated reproduction machine, that has a total sheet capacity of typical prior art collators but yet is smaller in physical size than heretofore realizable.
Still referring to online collators, there is a built-in operator inconvenience and increased cost in unloading these collators. For example, for a 20 bin collator, which is loaded to capacity, 20 separate motions are required, by an operator or other means, to unload, and for those collators not having automatic stapling and/or unloading, the operator will have to take care not to mix the sets by either stapling each set as it is removed, or by stacking the sets, offset from one another, to clearly demarcate them. It is clear that the foregoing actions and cautions, manually or otherwise, are time consuming, wasteful and expensive.
Thus, there is a need in the prior art for a collator of the online type having a capacity of the typical prior art collators that does not require unloading, in the prior art sense, and that provides not only collated sets but sorted and stacked sets readied for convenient removal, manually or otherwise, in a single motion rather than several motions.
It is realized that prior art collators of the online type will suffice for most job requirements in a typical office environment. However, there are job requirements that cannot be satisfied by a collator having a plurality of discrete bins, and, for example, a maximum set capacity of 20 and a maximum sheet capacity of 100 sheets per set giving a total sheet capacity of 2,000.
In a typical office environment, there are jobs that require the number of sets to be more than 20, but rarely require more than 100 sheets per set. Thus, prior art online collators have limitations in job flexibility characterized by the number of discrete bins and the sheet capacity of each bin.
As a consequence, there is a need in the prior art for an online collator having substantially infinite job flexibility limited only by the total number of sheets in a job rather than the total number of sets in a job, or the total number of sheets in a set.
As previously mentioned, there is another well known technique of collating, termed "offline collation" wherein the collators derived therefrom are generally complete within themselves. Since these collators are not designed to operate and interface with a host reproduction machine, they are generally larger in size, and, accordingly have more discrete bins and more sheets per bin capacity than online collators.
Using the offline collation technique, the general procedure is to produce from a multipage document, all of pages 1, then all of pages 2 and so forth. Then, a sorter is generally used to sort and stack like pages by jogging the sets to demarcate between the pages 1, the pages 2 and so forth. The sheets are then taken, or transported to the offline collator whereat all of the pages 1 are put into a bin, and all of the pages 2 are put into another bin and so forth. Finally, the offline collator operates to take pages out of each of the bins to make a collated set. The process is continued until the desired number of sets have been made.
In order to acquire the additional sheet capacity possible with offline collators, the aforementioned inconveniences are contended with in the special applications warranting the use of such a collator. Nevertheless, this collation technique is still limited to the number of discrete bins in the collator. Thus, the total sets in a job generally cannot comprise more pages of a like kind than there are discrete bins.
Hence, there is a need in the prior art for an offline collator having substantially infinite job flexibility limited only by the total number of sheets in a job rather than the total number of sets in a job, or the total number of sheets in a set, and at the same time be smaller in physical size than prior art offline collators with compatible total sheet capacity.